1. Technical Field
The present invention relates to a heat exchanger, a light source device, a projector and an electronic apparatus.
2. Related Art
Projectors have been known as an image projecting device.
The projectors each include a light source and an optical modulation panel which modulates light from the light source for each pixel. The projectors project the light modulated by the optical modulation panel on a screen to display an image.
Recently, LEDs (light-emitting diodes) or LDs (laser diodes), which have characteristics such as immediate lighting and long lifetime, have been considered for use as a light source for the projectors.
However, the LEDs and the LDs generate an extremely large amount of heat and an area of a portion of the LEDs and the LDs from which the heat is generated is extremely small compared with light sources in the related art, which requires a heat exchanger capable of absorbing the large amount of heat from the extremely small area.
As such a heat exchanger, a heat exchanger having a below-described arrangement is known (see, for example, JP-A-2005-166855).
This document discloses the heat exchanger that includes fins inside and circulates a cooling medium inside such that heat is exchanged between the fins and the cooling medium. For the heat exchanger, thin plate members for forming the fins and spacers that are held between the fins for spacing the fins are prepared. The fins and the spacers are made of a metal having a high thermal conductivity and formed by punching. The thin plate members and the spacers are alternately layered and then integrated as a whole by brazing. Consequently, small passages are formed between the fins. While the cooling medium flows through the small passages, heat is efficiently exchanged between the fins and the cooling medium. Since the fins can be processed to be thin, the heat exchanger can have high heat exchange efficiency.
However, as disclosed in the document, the arrangement in which the thin plate members and the spacers are layered requires many joint surfaces. Specifically, one small passage needs two joint surfaces. Such joint surfaces have a low thermal conductivity, hindering heat of a heat generating body from diffusing in a direction in which the thin plate members are layered. Accordingly, fins far from the heat generating body may not become hot enough, so that the thermal conductivity to the fluid may be lowered, thereby lowering the heat exchanging capability of the heat exchanger.
Further, the number of the fins and the spacers is very large, which may cause an increase in component costs and a decrease in assembling efficiency.